Several known desings of glass equipments have been proposed in the past to extract chemical substances from a solid, liquid or gel state. In general terms, the chemical extraction is carried out by two possible processes: continuous and discontinuous. For example, the methods for extraction and concentration of substances from samples such as: water environmental contaminants, plants and biological sample related medicines, are carried out in two different apparatus, one for the extraction process and the other for the separation process or occasionally, using a combined extractor/separator apparatus.
Therefore, the chemical substances to be extracted from a sample are dissolved by means of steam or a solvent in a continuous extraction apparatus, within a confined extraction space containing the material having the extractable component. The extracted substance is dissolved with the solvent within this extraction space and can be directed as an extract/solvent mixture to a reaction flask in a cyclic process in which the extract will be exposed to a solvent boiling temperature for extended period of times. This extraction method has been implemented in the industry for the last 120 years using a Soxhlet extractor, which establishes an automatic cycle for returning the extract towards the reaction flask using a siphoning system as the German Institute of Standard 12602 that occurs when the same solvent level with the content within the extraction space is reached. Thus, steam from the solvent reaches the extraction space in the conventional Soxhlet extractor when the solvent reaches its boiling temperature. This causes the condensate to still be hot when it drips through the sample, wherein the extracted substance is then siphoned towards the reaction flask where the solvent will be boiling. This extraction method is well suited for processes where the sample density is greater than the solvent density, as well as in molecules with high molecular weight. However, it shows poor efficiency with respect to the quality and purity of the extracted product in samples having densities lower than solvent density or in samples susceptible to high temperatures, such as biological substances, proteins, enzymes, etc. . . .
A similar extraction method known as “enriched extraction” is implemented using a Gregar extractor, developed at the Argone National Laboratory, Chemical Engineering Division where the continuous extraction principles previously explained are evident in the instrument design and its related methods. However, one disadvantage found in the conventional continuous extraction apparatus lies on the difficulty to perform the extraction through the supply of a fluid in two directions at the same time and the lack of monitoring the fluid temperature before it reaches the sample inside the extractor. Therefore, when more than one solvent is needed for extracting a substance of interest, the ideal process to reduce the working time would be to supply a mixture of solvents in a single step considering that more than one fluid will condensate over the sample if the boiling point of the mixture components is too close so that, additional work would be necessary to separate the extract contained on the mixture.
Previous apparatus have been designed to equilibrate the density difference between the solvent and the sample, which requires additional work in order to maintain the level of each component avoiding a fluid in opposite direction within the apparatus and the extract/solvent pressure are leveled in a hydraulic pressure equilibrium between two phases. To achieve such equilibrium, some previous extracting apparatus have components and additional designs that allow an operator to equilibrate these differences with some degree of operational risk. Thus, such extracting apparatus are subjected to special operational care directly related to the design and the assembly of the equipment to reach an equilibrium between the extract and the solvent volume, through a component or a piece that balances the hydraulic pressure inside the extractor and that satisfy the proportional relationship:Sh×Sρ=solvh=solvρ  (1)Where S=sample, h=height, ρ=density, solv=solvent.
However, a technician operating an equipment designed to satisfy equation (1), will not always be mindful of reaching the ideal level of the relationship sample:solvent that satisfy the balance between them according to design parameters that operate over all the parts of the equipment.
Therefore, it is desirable to have a conventional extraction equipment and a related method that simplifies the process with a design that allows an operator to balance the level of liquids and the hydraulic pressure in a quick, simple and safe manner.
When a pure solvent or a mixture of solvents is heated in a reaction flask, steam generated creates a lineal or crossed flow inside a conducting cylinder or over an interfering sphere, exhibiting a complex pattern according to thermodynamics. Liquids and gases share two intensive properties (density, d, and viscosity, ρ) directly related to their fluidity and velocity inside a transporting system. However, a gas is more fluid than its original liquid in a transporting phenomenum and thus, its viscosity, which is defined as the resistance that a part of the fluid shows to the displacement of the other, controls the process. Viscosity is produced by a cutting effect of a layer of fluid when displacing over other and is completely different than the so called intermolecular attraction. Assuming that a liquid stratifies in molecular planes, a plane's area is defined as A, and the interplanar distance as dy. Also assuming that each plane moves to the right with velocities v1, v2, etc., where each value is greater than its predecessor by increment dy. The flow occurring according to this is called laminar, and is different than the turbulent where plane parallelism is not observed. In the laminar flow, the force required to maintain a stationary velocity difference dv between two parallel planes is directly proportional to A and dv, and is inversely proportional to dy. Therefore:
                    f        =                  η          ⁢                                          ⁢          A          ⁢                                    ⅆ              v                                      ⅆ              y                                                          (        2        )            where f=fluid force, η=fluid viscosity coefficient, or simply fluid viscosity, the amount dv/dy in equation (2) refers to the cut velocity, Vc, while the relationship f/A, force per unit of area is called the cutting force, F. Thus, in terms of Vc and F equation (2) transforms into:η=F/A  (3)In this way, both equations (2) and (3) could be taken as expressions that define η and the practical application of these properties depends on the validity of a series of experimental assumptions, especially when the flow is laminar.
When designing a fluid transportation system, the onset conditions for turbulent flow depends on the magnitude of a certain combinations of experimental variables pertaining to a pure number called the Reynolds, Re. For a flow through a large pipe, cylindrical and lineal this number is proportional to:
                              R          e                =                  r          ⁢                                          ⁢          v          ⁢                                          ⁢                      ρ            η                                              (        4        )            where ρ is the fluid density and r is the pipe radio. It has been found empirically, that a laminar flow is always obtained in the same pipe when Re is less than 103, by virtue of the magnitude of any individual variable, r, v, ρ, η. Also, the laminar flow of a fluid depends on the regularity of the wall surface and the entrance form of the pipe, as well as on the internal length L′ of the transition region, since it is very important that this transversal section be very small in comparison to the pipe length, in a relationship:
                              L          ′                =                              1            4                    ⁢                      R            e                    ⁢          r                                    (        5        )            where r is the pipe radio and Re is the Reynolds number. It is inferred from this relationship, that the pipe must be tight to obtain a laminar flow and the Reynolds number could be considerably reduced if the pipe is substantially curved.